Fix VarDecls for tuples. Closes #99. I've implemented it this way since it doesn't require any changes in the frontend. However, I think having TypeTuple expressed as LLVM struct types would make much more sense and open the door to tuple lvalues.

module globals1;
extern(C) int printf(char*, ...);

char[] gstr = "hello world";

void main()
{
    printf("%.*s\n", gstr.length, gstr.ptr);
    char[] str = gstr;
    printf("%.*s\n", str.length, str.ptr);
}